medium CVSS 5.5 EPSS <0.1%

CVE-2021-47330·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: tty: serial: 8250: serial_cs: Fix a memory leak in error handling path In the probe function, if the final 'serial_config()' fails, 'info' is leaking. Add a resource handling path to free this memory.

Severity
medium
Software
Kernel
Fixed in
5.13.4
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 1% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

From: 5.13

Until: 5.13.4

Fixed in: 5.13.4

How to fix this CVE

Update your Linux kernel to version 5.13.4 or later to resolve a memory leak in the serial_cs driver's error handling path. This vulnerability affects systems using the 8250 serial device driver when configuration operations fail during device probe. Apply the kernel update through your distribution's package manager and reboot your system to ensure the patch takes effect.

sudo dnf update kernel kernel-headers kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r — verify it is 5.13.4 or later
  2. Identify if serial_cs driver is loaded: lsmod | grep serial_cs — if present, your system may be exposed
  3. Check dmesg logs for serial device probe failures: dmesg | grep -i 'serial\|8250' — look for configuration error messages
  4. Verify the patch was applied: grep -i 'serial_config' /boot/config-$(uname -r) — confirms driver is compiled; reboot and re-run uname -r to confirm new version is active

FAQ

What is CVE-2021-47330?

CVE-2021-47330 is a memory leak vulnerability in the Linux kernel's 8250 serial device driver (serial_cs module) that occurs when the serial configuration operation fails during device initialization, causing allocated memory to not be properly freed.

Is CVE-2021-47330 being actively exploited?

No, CVE-2021-47330 is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, the memory leak can degrade system stability over time if affected devices repeatedly fail probe operations.

What versions of Kernel are affected by CVE-2021-47330?

Linux kernel versions 5.13 through 5.13.3 are vulnerable. The vulnerability is patched in kernel version 5.13.4 and all subsequent releases.

How do I check if my server is vulnerable to CVE-2021-47330?

Run 'uname -r' to check your kernel version; if it returns a version between 5.13 and 5.13.3, your system is vulnerable. Additionally, run 'lsmod | grep serial_cs' — if the serial_cs driver is loaded, the vulnerability is exposed on your system.

Does Defensia detect CVE-2021-47330?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47330 will appear in your dashboard with remediation steps.

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References

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